Process fob the production of syn



Patented Dec. 13, .1938

UNITED STATES PATENT OFFICE PROCESS FOR THE PRODUCTION OF SYN- THETIC DRYING OILS Alexander Schwarcman, Buffalo, N. Y., aleignor to Spencer Kellogg and Sons, Inc., Bnflalo, N. Y., a corporation of New York No Drawing. Application October 25, 1937, Serial No. 170,957

15 Claims. (Cl. 260-407) This invention or discovery relates to artificial w th a specia y p epa ed h y a ive i er's drying oils and methods oi. roducing same; and t d t e p oduct w a n y m s rom it comprises a method of converting castor oil into ch t was imprac ic ble o ep rate t e ea th a drying oil wherein castor oil is heated with in y s p e way a d in which the qu p e 5 a suitably prepared catalyst at a temperature of was not a good drying 1 5' about 350 to 500 F. until a substantialincrease In this operation, and others, the attempt has in iodin number occurs, the catalyst is removed, b en to so d ect y from cestcr oil to a as by filtration, leaving a clear oil miscible with merciel drying This s o p a t ca le. hydrocarbons but having incompletely developed ut it s e y ff cu t as a c e c a p p 1. drying properties, and thi intermediate 11 i tion because of the exact control oi! conditions n heated to a temperature or about 600 F. to required. In a prior and copending application, stabilize it, to develo drying power and to body Serial N 3 w w th t e r s nt app ithe oil; and it comprises suitable catalysts tor cation has certain matter in common, I have usein the process and a method 01' preparing described such a method; castor oil carrying 1 them; and it comprises as new materials the inabout 1 D cent Suspended Sodium bisulfflte ll termediate oil and the bodied drying n proing carefully heated under a good vacuum until duced; all as more fully'hereinafter set forth and the (1111 number 668888 150 increase p y- All as claimed. this time the oil produced is thin enough to per- It is known that castor oil is largely composed mit ready removal of the catalyst and-is a dry- 20 of riclnolein, which is the triglyceride of ricinoleic 8 It however. i100 thinbodled most acid. This acid has the empirical to ul uses and in practice it is polymerized by heat to ClsH3403; it has a double bond between C9 and i e it t e dy usuallrwented in h trade- C10 and is further characterized by an alcoh li In the present invention I operate somewhat hydroxyl group on C7. Because of the alcoholic y- I catalyze the 011 but not character imparted b this hydroxyl group, castor u e p e y. h a su p e catalyst. 25 oil is soluble in alcohol and other oxygen-conmove the catalyst d de p d y g powe by taining solvents and it is compatible with vara further heat treatment. This heat treatment nish and lacquer compositions having alcohol or is ordinarily s u d t e a commercial ketones as solvents. Castor oil is not miscible, body t t e A remarkable result of this onso however, with hydrocarbon solvents, including eration is that at the time the catalyst is repetroleum oils and lubricating 0115. moved the oil is actually thinner and less viscous Sometimes it is considered desirable to blend than the original oil. This materially facilitates castor oil with ordinary lubricating 011. For removal of the catalyst. I have found that remaking these composite lubricants, castor oil can moval of the catalyst at this stage is important be g ven miscibility by mild pyrolysis or by from the standpoint of process control, as all 35 esterifying the alcohol groups. Generally, howc talysts have other actions than simple dehyever, it is simply heated with a catalyst. Any of in P r icular, a polymerizing r the many catalysts used in making ether or ethylthickening action-which tend to become preene from alcohol (acids, acid salts, activated dominant p n Prolonged heatingfullers earth, alumina, etc.,) can be used, though In detail, in thepresent invention I subject 40 there are but few giving a smooth and eoncastor oil to a two-stage operationor two-stage trollable action without discoloration or Iar-goheating, firstln the presence of a catalyst and ing changes in the oil. Th search for a really secondly in its absence. The oil is heated with good catalyst is still active. a solid. catalyst kept in suspension by agitation One difficulty in the operation is avoiding the until the development of foggy bubbles of steam 45 development of new double bonds; it new ethylslflckens 688888 and until the 101111! number ene linkage in the ricinoleic groups. This causes has ased about 0 pe c say from to ready oxidizability and drying power; both highly or or higher. This produces .an interundesirable. mediate oil which has substantially no utilizable 50 Attempts to utilize this double bond reaction drying P p it Will not dry to a d, 0 50 to convert'castor oil into a synthetic drying oil tacky varnish film. Nor is it particularly stable. have not been commercially successful; partly Ordinarily the operation is so conducted that not because of catalyst difiicultles and partly beall the castor oil is converted. there being usually cause of non-recognition of necessary conditions. about 5 or 10 per cent residual ricinolein, or a 55 In one method, for example, castor oil was heated corresponding amOimt mixed fl y es 7- I ing ricinoleic acid. This is usually advantageous in that it provides a factor of safety against fargoing reactions, and moreover gives a desirable elasticity to dried varnish films produced from the finished oil. If desired, I may so conduct the catalytic heat treatment that conversion is complete, however.

This intermediate oil is, as stated, of a conly the conditions commercially used in making stand oil from linseed oil: that is, keeping the oil at a temperature of 550 to 600 F. for 2 to 6. hours, until it acquires the desired body. In the first heating with the catalyst, the temperature used is much lower, being on the order'of 350 to 450 F.

In the two-stage operation described, as an academic matter, a wide variety of materials may be used to catalyze the removal of hydroxyl and the'production of ethylenic union in the first stage. Practically, however, the choice is limited by the necessity of avoiding side reactions, darkening, undue thickening, etc. The best material I have found is a composite catalyst; a body of finely divided porous inert mineral or earthy matter (fullers earth, kieselguhr, alumina, etc.) containing a very little free acid; enough to give a definite but faint acidity. An acid treated fullers earth washed to neutrality will catalyze the desired actions without side reactions but it is too slow. On the other hand, free acids and acid-reacting compounds, and particularly sulfuric acid and sodium bisulfate, when used alone in sufiicient quantity, catalyze the dehydronlation energetically; too energetically in fact. It is difllcult to avoid, among other undesirable phenomena, darkening of the oil and development of a high acid number. With my new catalyst, an earthy material carrying .a mere trace of free acid, a good clean catalysis can be effected without side reactions and without darkening the oil or increasing its acid number. While sulfuric acid alone inevitably produces darkening in what ever way it may be added to the oil, sulfuric acid used in minute amount with the earthy material .inmycatalysthasnosucheifect. Inawayof speaking, the acts as a bulking agent and allows even distributions! an extremely'minute amount of acid-an amount too small to efiect the desired dehydrolylation by itself. The earthy material and the incorporated acid together give an effect which is not given or approximated by either singly.

' ll'or the carrier, I have found it particularly advan eous to employ the inexpensive commercial of fuller's earth or These b themselves exert no dehydroxylating r oil, evenwhen heated withtheoil at higher M- peratures than are employed in my new processand for periods longer. With the selected earthy-carrierl ordinarily employ sulfuric acid because of its availability and low cost; but other acids, both mineral and organic, including acetic-acid, may be' used in place of thesulfuric acid. Sodium blsulfate may -.alsobeused,asinmy'priorinvention,bntin 7 deto'the desired temperature before the catalyst much smaller quantities. than are there scribed-sayabout lopereentaagreat. Itis no better than sulfuric acid,however, andislum 1i convenienttouseinimpregnatingtheearthwith theoll about 50'per cent in about 1.57s

minute but-exact amounts. When using sulfuric acid, I find it desirable to employ the acid in an amount corresponding to about .05 of one per cent of the oil treated, with a much larger amount of carrier; enough to give about 2 per cent by weight on the oil treated. For example, in the catalysis of 2000 pounds of castor oil I find it advantageous to employ about 40 pounds of clean kieselguhr or other inert porous earth carrying about one pound of concentrated sulfuric l acid. The actalyst may be prepared by suspending the carrier in water, adding the acid, mixing thoroughly, filtering, drying and powdering, or it may be prepared by adding the acid directly to the dry pulverulent carrier.

The amounts of acid and total catalyst specified in the preceding paragraph may be varied if I desired. A larger proportion of acid accelerates the reaction to some extent, but also darkens the product and is therefore undesirable. I have not found that .it was advantageous to use any larger percentages of earthy carrier with the stated quantity of sulfuric acid, and I belive that about .05 per cent of acid calculated on the oil and about 2 per centof total catalyst are the most effective 26- andmost economical proportions to employ. It is to be understood, however, thatv my invention is not limited to the use of these particular quantitles.

acid, I find it advantageous to employ a somewhat larger amount, as the action of acetic acid on the oil is lessviolent than the action of sulfuric acid, and the reaction may therefore be accelerated without producing excessive darkening. I find that it is safe, and in fact advantageous, to

employ amounts of acetic acid totaling up to about 0.15 per cent calculated on the oil, and..- when using this amount of acid I find it advantageous to employ about 3 per cent, on the oil, of

total catalyst.

In another modification of my invention, the

carrier is washed substantially free of acid before it is heated with the 011. For example, American iullers earth having no catalytic effect on the oil by itself may be suspended in three timesits weight of water, and a few per cent of hydrochloric or sulfuric acid may then be stirred in. The earth is then filtered from the acid liquid and washed repeatedly until the wash water is neutral. The earth is then dried and powdered and can be used as a slow catalyst. But it is better to acidlfy it.

When employing my catalyst containing about .05 per cent of acid calculated on the oil, a mix- 66 ture of oil and catalyst (about 2 per cent) is brought up to a temperature of approximately 400l". At a temperature of about 380 F. white foggy bubbles begin to appear. Formation and extrication of water by the hydroxylating action 00 becomes quite violent at a temperature between 420 and 460 F.'usually about 440 F.and

energetic action is substantially completed at this temperature in about half an hour. I find it desirable to continue the heating at this tem- 06 it makes very little diiference whether the cata- 70 lyst is added to the cold oil or the oil is heated.

In this catalyzing operation the iodin value of When using acetic acid in the place of sulfuric 30 hours or less. Most of the increase from 85 to 125 or 140, for example, takes place within the first half hour after the reaction temperature is reached,

The above description applies principally to operations at atmospheric pressure. It is sometimes desirable to operate under vacuum, although this is seldom necessary with my new catalyst. Operating under vacuum has the advantage, however, that it yields a product of somewhat lower acid value, and the acid value can be controlled within substantially any desirable range by bleeding a small amount of inert gas, such as CO: or nitrogen, into the 011 during the heating under vacuum. I generally find it advantageous not to apply vacuum until substantially the desired iodin value is attained by heating with the catlyst at atmospheric pressure for about half an hour, for example. The remainder of the first heating stage can then be conducted under suitable vacuum, with or without bleeding in a small amount of inert gas, to reduce the acid value of the intermediate oil.

To produce the best results, it is essential that the intermediate product above described be polymerized or subjected to further heat treatment in the complete absence of catalyst. .The catalyst is therefore removed from the intermediate oil by filtration or centrifuging, and one of the advantages of my catalyst is that it can be readily removed. The oil, after removal of the catalyst, is miscible with mineral oils and hydrocarbon solvents and has a high iodin number. At this stage, however, the oil will not dry in the sense of making a satisfactory varnish film, either with or without the addition of driers. Its drying power, so to speak,-is only potential.

After removal of the catalyst this clear intermediate oil of low viscosity is subjected to a temperature on the order of 550 to 600 F. at atmospheric pressure or under vacuum, the most desirable temperature being about 590 F. This temperature is maintained for a suificient period, such as about two to six hours, to convert the intermediate oil into a final product which is a true drying oil and is polymerized to some extent, and may also be considered a stand oil if the heating is suificiently prolonged. This oil has exceptionally good drying power, and with the addition of .01 per cent of catalytic drier such as cobalt linoleate, it will dry to form a smooth, glossy, elastic waterproof film in about one to three hours.

The properties of this final oil are unique. Like linseed stand oil it yields rubbery linoxynlike substances on air blowing, but like Chinawood oil it seems to set in a varnish film largely by internal actions, and it gives a waterproof film, which linseed oil will not. Unlike Chinawood oil and like linseed oil, it does not gel or coagulate on heating. The new oil is applicable to most of the purposes for which China-wood oil may be employed, and is also applicable to most of the purposes for which polymerized linseed oil is used, including the manufacture of.

linoleum. Y

As a specific example of the operation of my invention, I will now describe the full cycle of operations involved in a particular two-stage conversion of castor oil to drying oil on a commercial scale. The castor oil used as a starting material was nearly water white in color, had a specific gravity of 0.9620, an acid value between 1 and 2, a saponiflcation value of 182.0, an iodin value of 86.0, and a viscosity of U on the Gardner-Holdt scale, corresponding to 6.27 poises. at 25 C. This oil was, of course, soluble in alcohol and insoluble in mineral oils.

Catalyst was prepared by uniformly incorporating one pound of concentrated sulfuric acid with 40 pounds of an ordinary commercial American type of fullers earth, which in itself has no dehydroxylating effect on castor oil at any known temperature, as described hereinabove. This catalyst was mixed with 2,000 pounds of the above castor oil, and heated in an open kettle with stirring. At a temperature below 400 F., dehydroxylation started, as was evidenced by the evolution of steam bubbles. At a temperature a little above 400 F., this reaction became quite violent and continued for nearly half an hour. The evolution of steam then continued at a much slower rate, and heating at a. temperature of about 440 F. was continued, with mechanical agitation, for about an hour more. The catalyst was then separated from the intermediate oil by filtration, and a sample of the oil was taken for testing. This oil had a very pale straw color, was insoluble in alcohol, and was soluble in mineral oils. Its specific gravity was 0.9468 and it had a viscosity of Q on the Gardner-Holdt scale,

corresponding to 4.35 poises. Its acid value was 5, saponification value 186, and iodin value 130. In similar runs with other batches of oil, acid values were obtained between 4 and 6, with saponification values of from 185 to 190, and iodin values from 125 to 140. The intermediate oil thus produced can be made to dry or form a film when enough catalytic drier such as cobalt is added, but the film remains soft and is not waterproof and is not a satisfactory commercial varnish film.

The intermediate oil just described was then given a further heat treatment in an open kettle at a temperature of about 590. F. for about 5 hours. The oil thus produced was still soluble in mineral oils and insoluble in alcohol and had a light amber color--a pale clear yellow. Its specific gravity had increased to 0.9600 and its viscosity to Z-2+ on the Gardner-Holdt scale, corresponding to about 38'poises. Its acid value was 9, its saponification value 192 and its iodin value 112. In other similar runs the acid value of the final product varied between 8 and i2, and the iodin value varied between 108 and 115. It is interesting to note that although the final oil had a viscosity considerably higher than that of the original castor oil, its specific gravity was lower. It is to be understood that the viscosity and other properties of the final oil can be varied by varying the length of the second heat treat ment. The final oil is a true drying oil which, with the addition of a trace of drier, dries in less than two hours to form a lustrous, elastic film which is truly waterproof and highly satis factory.

One of the features of my invention is that it produces a drying oil of very light color. It is sembles tung oil or China-wood oil in a greatmany respects. Because of this resemblance, it is sometimes desirable to blend the oil with Chinawood oil. This may be done after the finished oil is produced as described hereinabove. As an alternative, I may mix China-wood oil and castor oil, in equal or other desired proportions, and put the mixed oil through the treatment above described. This produces a new drying oil which has many advantages. Other oils containing substantial proportions of ricinolein may be treated similarly to castor oil, with similar results.

What I claim is: a

1. In the production of a drying oil from castor oil, the process which comprises heatingcastor oil with a suspended solid catalyst at a temperature of about 350 to 500 F. until there is a large increase in the iodin number, said catalyst being selected from the group consisting of sodium bisulfate and mixtures of earthy materials which have substantially no polymerizing or dehydroxylating effect on castor oil with minor amounts of acid material insufliclent to dehydroxylate the oil, removing the catalyst, and continuing the heating at a temperature of about 550 to 600 F. to produce stabilization and develop drying properties.

2. The process of claim 1 wherein the suspended catalyst comprises said earthy material and a trace of free sulfuric acid. I

3.The process of claim 1 wherein the suspended catalyst comprises said earthy material and a trace of free acetic acid.

4. The process of claim 1 wherein the .suspended catalyst comprises said earthy material and about .05 per cent sulfuric acid calculated on the oil.

5. In the process ofclaim 1, performing the. 3 first heating at atemperature of the order of 450' F. maintained for about 1.5. hours.

6. In the'process of claim 1, heating the castor oil with the catalyst at atmospheric pressure until the desired iodin value is attained and continuing heating under vacuum to reduce the acid value.

7. In a process of producing drying oil from castor oil, preparing a catalyst by contacting finely divided earthly material which in itself has substantially no polymerizing or dehydroxylating effect on castor oil with a smaller quantity of acid material not exceeding about 10 per cent of the weight of the earthy material, adding-to the castor oil to be treated a quantity of said catalyst not exceedingabout 5 per cent of the material is acetic acid.

weight of on and containing said acid material in an amount insufilcient by itself to dehydroxvylate the oil and not exceeding about 0.5 per cent of the weight of oil, heating the castor oil and catalyst together at a temperature between 350 and 500 F. until evolution of water-vapor substantially ceases, removing the catalyst from the intermediate oil so produced, and heating the intermediate oil at a temperature of the order of 550 to 600 1". for a period sufllcient to produce a polymerized drying oil.

8. The process of claim 7 wherein the quantity of catalyst employed is about 2 per cent of the weight of the oil and the acid matierial is sulfuric acid amountingv to about 0.05 per cent of the weight of the oil.

9. The process of claim '7 wherein the'quantity of catalyst employed is about 3 per cent of the weightoi' the'oil and the acid material is acetic acid amounting to about 0.15 per cent of the weight of the oil. 10. The method of preparing a catalyst forthe conversion of castor oil into an artificial dryingoil, which comprises contacting a finely divided earthy material which in itself has substantially no polymerizing or dehydroxylating eflect on castor oil with a quantity of acid material insufllcient to effect the desired dehydroxylation of the oil at temperatures of 350 to 500 F.

11. The method of claim 10, wherein the earthy material is mixed with a quantity of acid amounting toless than 0.3 per cent of the weight of .the'castor oil to be treated.

12. As a catalyst for the conversion of castor oil to an intermediate oil having potential drying properties by heating at temperatures of about 350 to 500? F., a finely divided, porous, earthy material which has substantially no poly- .merizing or dehydroxylating effect on castor oil and having dispersed thereon an amount of acid material which is insuillcient in itself to efiect the desiredpconve'rsion.

13. The catalyst of claim 12 wherein the acid,

material is sulfuric acid.

14. The catalyst of claim 12 wherein the material is sodium bisulfate.

15. The catalyst of claim 12 wherein the acid acid . ALEXANDER SiC I-IWARCMAN. 

